L. Calabrese, A. Mucciolo, A. Zanichelli & M. Gustin / Conservation Evidence (2020) 20, 35-39

Effects of nest boxes on the most important population of red-footed Falco vespertinus in

Licia Calabrese1*, Alessandro Mucciolo1, Andrea Zanichelli1 & Marco Gustin2

1Local Conservation Group LIPU- Birdlife Italia, Via Udine 3/a, 43122 , Italy 2Conservation Department LIPU-Birdlife Italia, Via Udine 3/a, 43122 Parma, Italy

SUMMARY The red-footed falcon is a near threatened , which breeds mainly in agricultural landscapes, typically nesting in empty corvid nests on trees. In Europe, this species is declining due to habitat degradation and agriculture intensification. The aim of our study was to determine the reproductive success and the increase in the number of nesting pairs after the installation of nest boxes. This study took place in the Italian , the southernmost part of the red-footed falcon’s breeding range. Nest boxes were provided in four locations, where were already breeding in corvid nests, to assess if this action could increase the falcon population and breeding success in the study area. After the deployment of 117 nest boxes from 2010 to 2018 the Parma population increased from 25 to 82 pairs, occupying up to 50% of available boxes in 2018. The breeding success remained unvaried over the study period with an average of 2.06 and 2.37 chicks fledged per pair in corvid nests and nest boxes respectively. It also did not differ between the two nest categories. These results could indicate that a lack of suitable nesting sites is a major limiting factor for the falcon population in the Parma province rather than lack of food.

BACKGROUND Hungary, falcons hunt over corn or sunflower fields The red-footed falcon Falco vespertinus is a in early spring (when crop height is short) and over raptor species, which breeds in wooded steppe, open alfalfa and cereal crops later in the season (Palatitz rural environments with a predominance of et al. 2018). The red-footed falcon is sometimes extensive cultivation and pasture with stands and colonial and exploits rookeries, artificial nest boxes rows of trees (del Hoyo et al. 1994). It is classified and solitary corvid nests for breeding (Palatitz et al. as a near threatened species on the IUCN Red List 2009, Chavko & Kristin 2017). The red-footed (BirdLife International 2018) and as a globally falcon’s natural nesting sites in Italy include magpie threatened Species of European Conservation Pica pica and hooded crow Corvus cornix nests. Concern (SPEC 1) (BirdLife International 2017). As with other falcon species (e.g. lesser The global population has been estimated at Falco naumanni, see Catry et al. 2013; Gustin et al. 300,000-800,000 individuals, with 30,000-64,000 2017), many eastern populations of red-footed pairs in Europe (BirdLife International 2017). In falcon use nest boxes (Fehérvári et al. 2015). These central Europe, their populations declined by 30– constitute one of the most common conservation 40% between 1990 and 2000 (BirdLife International actions for red-footed falcons in heavily transformed 2004). This decline is attributed to habitat landscapes and are useful for research purposes, as degradation, pesticide spraying, loss of nesting sites, the artificial nests can be placed in accessible and the conversion of grasslands to agricultural locations to better enable behavioural, ecological or fields (BirdLife International 2018). Over 90% of conservation research (Bragin et al. 2017). The use the Italian population breeds in the Emilia Romagna of nest boxes as a conservation measure has also region of the Parma province (Nardelli et al. 2015). been successful in 65% of the 22 studies (from nine A serious threat to the red-footed falcon population countries) assessed on the Conservation Evidence is soil sealing: the destruction or covering of soil by website layers of completely or partly impermeable artificial (www.conservationevidence.com/actions/489). material such as buildings, asphalt, or concrete Our aim was to assess whether the Italian (Huber et al. 2008). This is an irreversible process population of red-footed falcon would benefit from and, in 2017, soil sealing increased by an average of the provision of nest boxes. The study site, which 12% (compared to 2016) in the municipalities includes six Natura 2000 sites and two nature surrounding and including the Parma province reserves, is located in the Parma flood plain (Figure (Rapporto ISPRA 2018). 1) and is characterised by an intensively managed The species does not need wooded habitats, only agricultural landscape. Cultivated crops, such as isolated trees for nesting and roosting. Generally, in cereals (corn, wheat, barley) and tomatoes, are our study area, they nested alone although, on one alternated with forage crops, such as alfalfa and occasion, two pairs were found nesting in the same grass, - often used for cattle feed. This area tree. In this region, hunting areas mainly consist of represents the western periphery of the red-footed alfalfa crop. However in other areas, for example in falcon’s range (Grassi et al. 1999, Sponza et al. 2001, Palatics et al. 2018). *corresponding author email: [email protected]

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ACTION discovery of the nest) in order to assess the breeding From 2009 to 2012 the authors were all involved success (number of fledged chicks per pair). in the LIFE Project “Interventions for life of Community interest in the Natura 2000 sites of the lower Parma plain” (Fior & Gustin 2012) that funded the installation of the first nest boxes and partially funded the subsequent 3 years of monitoring. Afterwards, all monitoring was carried out on a voluntary basis. Monitoring covered approximately 580 km2 and was carried out during the breeding season from May to August (40 days per year during the breeding season). Every road within the study area was travelled by car or on foot (if inaccessible by car) and once one individual falcon was spotted (hunting or resting), it was followed in order to locate the nest (if present). Stops Figure 1. Study area in the Parma province were made at previously known nesting sites in including the four main red-footed falcon nesting order to assess the number of active nests. sites where the nest boxes were placed and the two Agricultural areas with rows of trees, isolated trees, nature reserves (NR). Special Protection Areas or groves were considered suitable for the species (SPA) and Special Areas for Conservation (SAC) and these were also checked for signs of nesting within the study area are also indicated. 1) SPA activity. Red-footed falcon nests were mapped at the IT4020019 Golena del Po presso Zibello; 2) SPA beginning of the breeding season (May-June) in IT4020018 Prati e ripristini ambientali di Frescarolo order to identify the most popular breeding sites e San Boseto; 3) SAC IT4020024 San Genesio; 4) within the study area and these were monitored at SAC-SPA IT4020022 Basso ; 5) SAC-SPA least once a week to assess breeding success. After IT4020017 Aree delle risorgive di Viarolo, Bacini di the LIFE Project ended in 2012, LIPU-BirdLife , Fascia Golenale del Po; 6) SAC-SPA carried out routine monitoring until 2018, using the IT4020025 Parma Morta. same methods. In addition, we compared reproductive parameters and breeding success Table 1. Number of nest boxes present in each (number of chicks fledged) in nest boxes and natural monitoring site from 2010 to 2018. In 2009 there nests using monitoring data collected in 2009-2018 were no nest boxes. Vi = Viarolo, Fr = Frescarolo, in the lower Parma plain. We then interpreted these Ba = Baganzola, Cr = Crociletto. results in the context of management programmes in Total Italy. Year Site Nest From 2010 to 2018 we placed a total of 117 nest Boxes boxes in four sites where the red-footed falcon had Vi Fr Ba Cr previously nested in high densities using natural 2010 27 36 0 0 63 nesting sites (corvid nests, Figure 1). Table 1 provides details of the number of nest boxes 2011 27 36 11 0 74 installed at each of the four sites. The sites were: i) 2012 25 36 11 0 72 Viarolo (44°53.958’N-10°16.583 E), consisting of a 2013 24 36 11 0 71 980 m row of black poplar Populus nigra and oak Quercus sp.; ii) Frescarolo (44° 58.506' N- 10° 2014 48 36 10 5 99 07.056'E), consisting of a 200 m long row of black 2015 57 33 8 5 103 poplar; iii) Baganzola (44° 53.676'N- 10° 17.763'E) 2016 59 37 6 5 107 consisting of a 700 m line of black poplar and oak; 2017 55 36 2 18 111 iv) Crociletto (44° 58.715'N- 10° 10.670'E) consisting of a 200 m row of black poplar. In order 2018 62 35 2 18 117 to simulate colonies, nest boxes were placed near existing corvid nests in clusters 10 – 20 m high on Nest boxes were cleaned once a year (October - rows of trees spaced 3 - 20 m apart. Boxes were February) before the arrival of red-footed falcons. fastened to the main tree trunk in locations Broken boxes were removed, replaced or repaired. accessible to the falcons and often close to a branch In order to assess whether the red-footed falcon that could be used as a perch. One single tree could population increased following the introduction of hold up to three nest boxes at different heights and nest boxes we first assessed the overall population aspects. trend (measured as the number of breeding pairs). The nest box design was selected using the The response variable was set as the number of recommendations of Kotymán et al. 2015 (Figure 2). breeding pairs per year while the explanatory Both nest boxes and natural nesting sites were variable was represented by the year. In this way we monitored throughout the breeding season with at established the relationship between population and least four visits to each occupied nest (from the years.

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Figure 2. Left: nest box design. Right: machinery used to install the nest boxes. All rights reserved. © Licia Calabrese.

We tested whether the proportion of pairs Figure 3. Number of breeding attempts in nest occupying nest-boxes (Nests in NB/total nests, boxes and natural nests. In red the regression trend Table 2) increased significantly during the study of the total breeding attempts across the years (with period by fitting a binomial generalised linear model corresponding R2 and p value), showing a significant using the proportion of pairs breeding in nest boxes positive upward trend. as the response variable and the year as the explanatory variable. We used paired t-tests to compare seasonal average breeding success (average number of chicks fledged per pair) between pairs breeding in nest boxes and in natural nesting sites (corvid nests). The relationship between the total number of breeding pairs and the number of available nest boxes was assessed using linear regression with the number of breeding pairs as the response variable and the number of nest boxes as the explanatory variable. All statistical tests were carried out using the open source program R (R Core Team 2019).

CONSEQUENCES The red-footed falcon population in the Parma Figure 4. Relationship between the number of plain increased during the study period. The number available nest boxes and the number of breeding of breeding pairs rose from 25 (in 2009) to 82 (in pairs with the linear trend. 2018). This rate of increase in the breeding population was significantly different from zero (R2 DISCUSSION = 0.87, d.f. = 8, p < 0.001, Table 2 and Figure 3). The red-footed falcon population in the Parma The nest box occupancy rate increased from 11.1% plain has increased significantly since the during the first year (2010) to 50.8% during the final installation of nest boxes in areas already frequented year of the study (2018) and doubled from the by the species. This trend was positively correlated second to third year and from the third to fourth year with nest box availability and this, together with our (Table 2). In 2018, 73.2% of breeding attempts analysis of the occupancy rate, suggests that the occurred in nest boxes and the proportion of pairs addition of nest boxes is an important factor occupying nest boxes increased significantly during promoting this population increase. This was also the study period (% deviance explained = 0.65, d.f. observed in the Hungarian population where two = 8, p < 0.01). The number of red-footed falcon thirds of red-footed falcons breed in nest boxes breeding pairs was positively correlated with the (Palatitz et al. 2015). In our study the occupancy rate number of available nest boxes (R2 = 0.74, d.f. = 8, increased after two years from the initial p < 0.01, Table 2 and Figure 4). deployment. This population increase, after new nest There was no significant difference in breeding sites were available, may indicate that the main success between pairs using nest boxes and natural limiting factor for this species is a lack of suitable nest sites (paired t-test: t = 1.36, d.f. = 8, p = 0.21) nesting sites, such as corvid nests on high trees (Table 2). (Cramp & Simmons 1980).

In addition, over the past 20 years, agricultural

operations in the Parma plain have intensified and

many trees and hedges have been removed.

Urbanisation and agricultural soil sealing in this area

increased over the same period. For example, in

2016/2017 in the municipalities of Sissa-

37 ISSN 1758-2067 L. Calabrese, A. Mucciolo, A. Zanichelli & M. Gustin / Conservation Evidence (2020) 20, 35-39 and (both included in the study area), soil In conclusion, providing nest boxes proved to be an sealing increased by 7% on average; Sissa-Trecasali important action (although it was the only one we is the municipality with the highest soil sealing in tested) for the red-footed falcon population in the the province (Rapporto ISPRA 2018). These Parma plain and, as such, is a conservation effort that processes may have reduced the availability of should be maintained. However, concentrating the nesting sites (mainly because of tree felling), forcing breeding pairs in only few areas may expose them to the falcon population to increasingly rely on localised threats, such as increased urbanisation artificial nests (Bragin et al. 2017). The Hungarian close to the colony or the removal of the rows of population also suffered a large decline until 2000 trees holding the nest boxes (either by natural or due to the lack of nesting sites as most of this anthropogenic causes). Natural nesting sites are population nested in rook's (Corvus frugilegus) decreasing with the removal of rows of trees as a nests, a species that also suffered a population result of agriculture intensification and soil sealing. decline (Palatitz et al. 2015). At present, breeding Therefore, it is important to influence agricultural success of the Italian population is high compared to policy in the area by promoting less industrialised the Hungarian and Slovakian populations, (Chavko agriculture by reducing soil over-sealing throughout & Kristin 2017, Palatitz et al. 2015) in both artificial the plain to provide more breeding sites and manage and natural nests. and increase the number of nest boxes. Nest sites One nest box costs approximately €60 and, should also be included in protected areas although including the cost to rent an appropriate machine for this could be limited by the high financial cost and installation and maintenance of nest boxes, the total effort required from conservationists and cost of this operation over 9 years was stakeholders to install and maintain nest boxes. approximately €10,000, (€1,120 per year). The greatest expenses were incurred during the first two years of the project (2010 and 2011) for the purchase of the first 60 nest boxes (Fior & Gustin 2012).

Table 2. Number (N) of red-footed falcon breeding pairs and breeding parameters. Where NN = natural nesting sites (corvid nests), NB = nest box. 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 N pairs 25 21 16 28 46 38 68 63 70 82 N Nest Boxes* - 63 75 73 71 99 104 107 111 117 N pairs in NN 25 14 6 11 17 10 21 17 19 22 N pairs in NB - 7 10Ÿ 17Ÿ 29 28 47Ÿ 46 51 60Ÿ N chicks fledged 48 18 36 72 128 111 132 152 160 195 N chicks fledged in NB - 7 25 42 95 89 81 114 112 148 Nests in NB/total nests (%) - 33.3 62.5 60.7 63.0 73.7 69.1 73.0 72.9 73.2 % occupied NB - 11.1 12.0 21.9 40.8 28.3 44.2 43.0 45.9 50.8 N breeding success# in NN 1.9 0.8 1.8 2.7 1.9 2.2 2.4 2.2 2.5 2.2 N breeding success# in NB - 1.0 2.5 2.5 3.3 3.2 1.7 2.5 2.2 2.5 Total+ breeding success# 1.9 0.9 2.3 2.6 2.8 2.9 1.9 2.4 2.3 2.4 *nest boxes available at the beginning of the breeding season ŸIn 2011, 2012, 2015 and 2018 a pair of red-footed falcon occupied a kestrel nest box, deployed for another study. The number of pairs in those years includes this pair. Therefore, N Nest Boxes available is increased by one compared with Table 1. # average number of chicks fledged per pair + nest boxes and natural nests

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ACKNOWLEDGEMENTS Grassi L., Licheri D. & Sponza S. (1999) We wish to thank all the volunteers involved in Nidificazione di Falco cuculo Falco vespertinus the fieldwork, mainly from the Parma LIPU’s Local in provincia di Parma. Avocetta, 23, 141. Conservation Group (in particular Germano Gustin M., Giglio G., Pellegrino S.C., Frassanito A. Balestrieri, Mario Pedrelli e Michele Mendi for their & Ferrarini A. (2017) Space use and flight extensive knowledge of the red-footed falcon) and attributes of breeding Lesser Falco LIPU UK for the very important economic support. naumanni revealed by GPS tracking. Bird study, In 2009-2012 LIPU was part of the LIFE project 64, 274-277. “Life07 Nat/IT/000499 Pianura Parmense” Huber S., Prokop G., Arrouays D., Banko G., Bispo (Interventi per l’avifauna di interesse comunitario nei A., Jones R., Kibblewhite M., Lexer W., Möller siti Natura 2000 della bassa pianura parmense). A., Rickson J., Shishkov T., Stephens M., Van den Akker J., Varallyay G., Verheijen F., 2008. REFERENCES Indicators and Criteria report. ENVASSO BirdLife International (2004) in Europe: Project (Contract 022713) coordinated by population estimates, trends and conservation Cranfield University, UK, for Scientific Support status. Cambridge, U.K. BirdLife International to Policy, European Commission 6th Framework (BirdLife Conservation Series No. 12). Research Programme. BirdLife International (2017) European birds of Kotymán L.S., Solt, E., Horvath P., Palatitz P. & P. conservation concern: populations, trends and Fehervari P. (2015) Demography, breeding national responsibilities. Cambridge, UK: success and effects of nest type in artificial BirdLife International. colonies of Red-footed Falcons and allies. Ornis BirdLife International (2018) Falco vespertinus. Hungarica, 23, 1-21. The IUCN Red List of Threatened Species 2018: Nardelli R., Andreotti A., Bianchi E., Brambilla M., e.T22696432A131939286. Brecciaroli B., Celada C., Dupré E., Gustin M., Bragin E.A., Bragin A.E. & Katzner T.E. (2017) Longoni V., Pirrello S., Spina F., Volponi S. & Demographic consequences of nest box use for Serra L. (2015) Rapporto sull’applicazione della red-footed falcons Falco vespertinus in Central Direttiva 147/2009/CE in Italia: dimensione, Asia. Ibis, 159, 841–853. distribuzione e trend delle popolazioni di uccelli Catry I. Franco A.M.A. Rocha P. Alcazar R. Reis S. (2008-2012). ISPRA, Serie Rapporti, 219/2015. Cordeiro A. Ventim R. Teodósio J. & Moreira F. Palatitz P., Fehérvári P., Solt S. & Barov B. (2013) Foraging habitat quality constrains (2009) European Species Action Plan for the effectiveness of artificial nest site provisioning Red-footed Falcon Falco vespertinus. BirdLife in reversing population declines in a colonial International for the European Commission. cavity nester. PlosOne, 8, e58320. Palatitz P. Fehérvári P., Szabolcs P. & Horváth É. Chavko J. & Kristin A. (2017) Foraging (2015) Breeding population trends and pre- opportunism and feeding frequency in the red- migration roost site survey of the Red-footed footed falcon (Falco vespertinus) in Slovakia: Falcon in Hungary. Ornis Hungarica, 23, 77–93. case study from 2017. Slovak Raptor Journal, Palatitz P., S. Solt & P. Fehervari (Eds.) (2018) THE 11, 31–41. BLU VESPER. Ecology and Conservation of the Cramp S. & Simmons K.E.L. (1980) Handbook of Red-footed Falcon. Budapest, MME. the birds of Europe, the Middle East, and North R Core Team (2019). R: A language and Africa: the birds of the western Palearctic. environment for statistical computing. R Oxford University Press, Oxford. Foundation for Statistical Computing, Vienna, del Hoyo J., Elliott A. & Sargatal J. Austria. URL https://www.R-project.org/. (1994) Handbook of the Birds of the World, vol. Rapporto ISPRA (2018) Consumo di suolo, 2: New World Vultures to Guineafowl. Lynx dinamiche territoriali e servizi ecosistemici. Edicions, Barcelona, Spain. Edizione 2018, Rapporti 288/2018. Fehérvári P., Sándor Piross I., Kotymán L., Solt S., Sponza S., Licheri D. & Grassi L. (2001) Horváth É. & Palatitz P. (2015) Species specific Reproductive behaviour and success of Red- effect of nest-box cleaning on settlement footed Falcon Falco vespertinus in North Italy. selection decisions in an artificial colony system. Avocetta, 25, 69. Ornis Hungarica 23, 66–76. Fior E. & Gustin M. (2012) Relazione monitoraggio faunistico. Life 07 NAT/IT/000499 PIANURA PARMENSE. Azione E2, pp: 1-51.

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